Lord Justice Brian Leveson releases 2,000-page report at the end of a media ethics inquiry triggered by revelations of tabloid phone hacking that expanded to engulf senior figures in politics, the police and Rupert Murdoch's media empire.

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A long-awaited report on the U.K. phone-hacking scandal said Rupert Murdoch's newspapers and other media were reckless in pursuing sensational stories.

Britain needs a new independent media regulator to eliminate a subculture of unethical behavior that infected segments of the country's press, a senior judge said Thursday at the end of a yearlong inquiry into newspaper wrongdoing.

Lord Justice Brian Leveson said a new regulatory body should be established in law to prevent more people being hurt by "press behavior that, at times, can only be described as outrageous." But Prime Minister David Cameron balked at that idea, warning that passing a new law to set up the body would mean "crossing the Rubicon" toward state regulation of the press.

Leveson issued his 2,000-page report at the end of a media ethics inquiry that was triggered by revelations of tabloid phone hacking and expanded to engulf senior figures in politics, the police and Rupert Murdoch's media empire.

His proposals will likely be welcomed by victims of press intrusion and some politicians, who want to see the country's rambunctious press reined in. But some editors and lawmakers fear any new body could curtail freedom of the press.

Cameron welcomed Leveson's proposal for a new regulator with powers to settle disputes, order corrections and fine offenders.

But he said that asking legislators to enshrine it in law meant "crossing the Rubicon of writing elements of press regulation into the law of the land."

"I believe that we should be wary of any legislation that has the potential to infringe free speech and a free press," Cameron told lawmakers in the House of Commons. "In this House which has been a bulwark of democracy for centuries, we should think very, very carefully before crossing this line."

Meanwhile, the chairman of the U.S. Senate Commerce Committee announced Thursday that he would pay close attention to the findings of the probe by newspapers owned by Murdoch and others, amid concerns that U.S. laws may have been broken, NBC News reported.

In an emailed statement to NBC News, Sen. Jay Rockefeller said he remained "deeply concerned that these companies may have violated U.S. laws and injured U.S. citizens.”

Leveson insisted in his report that politicians and the government should play no role in regulating the press, which should be done by a new body with much stronger powers than the current Press Complaints Commission.

He said "what is needed is a genuinely independent and effective system of self-regulation."

But Leveson said it was "essential that there should be legislation to underpin the independent self-regulatory system."

"The ball moves back into the politicians' court: they must now decide who guards the guardians," he said.

He said the new body should be composed of members of the public including former journalists and academics — but no serving editors or politicians. It should have the power to demand prominent corrections in newspapers and to levy fines of up to 1 million pounds ($1.6 million).

Critics of the tabloid press generally welcomed the report.

Former Formula One boss Max Mosley, who sued Murdoch's News Corp. for invasion of privacy over claims he had taken art in a Nazi-themed orgy, said Leveson's report went in the right direction, although "I would have liked to see more."

Campaign group Hacked Off said Leveson's proposals "are reasonable and proportionate and we call on all parties to get together to implement them as soon as possible."

Cameron set up the Leveson inquiry after revelations of illegal eavesdropping by Rupert Murdoch's now-defunct News of the World tabloid sparked a criminal investigation and a wave of public revulsion.

The furor erupted in 2011 when it was revealed that the News of the World had eavesdropped on the mobile phone voicemails of slain schoolgirl Milly Dowler while police were searching for the 13-year-old.

Murdoch shut down the 168-year-old newspaper in July 2011. His U.K. newspaper company, News International, has paid millions in damages to dozens of hacking victims, and faces lawsuits from dozens more, from celebrities, politicians, athletes and crime victims whose voicemails were hacked in the paper's quest for scoops.

Leveson heard evidence from hundreds of journalists, politicians, lawyers and victims of press intrusion during months of hearings that provided a dramatic, sometimes comic and often poignant window on the workings of the media. Witnesses ranged from celebrities such as Harry Potter author J.K. Rowling and Hugh Grant — who both complained of intrusive treatment — to the parents of Dowler, who described how learning that their daughter's voicemail had been accessed had given them false hope that she was alive.

Leveson said that the ongoing criminal investigation constrained him from accusing other newspapers of illegal behavior, but argued there was a subculture of unethical behavior "within some parts of some titles."

While many editors have denied knowing about phone hacking, Leveson said it "was far more than a covert, secret activity, known to nobody save one or two practitioners of the 'dark arts.'"

More broadly, he said newspapers had been guilty of "recklessness in prioritizing sensational stories almost irrespective of the harm the stories may cause."

"In each case, the impact has been real and, in some cases, devastating," the judge said.

The hacking scandal has rocked Britain's press, political and police establishments, who were revealed to enjoy an often cozy relationship in which drinks, dinners and sometimes money were traded for influence and information.

Several senior police officers resigned over the failure aggressively to pursue an investigation of phone hacking at the News of the World in 2007. But Leveson said that "the inquiry has not unearthed extensive evidence of police corruption.

Leveson said over the past three decades, political parties "have had or developed too close a relationship with the press in a way which has not been in the public interest."

He acquitted senior politicians of wrongdoing, but recommended that political parties publish statements "setting out, for the public, an explanation of the approach they propose to take as a matter of party policy in conducting relationships with the press."

Cameron is under intense pressure from both advocates and opponents of a new law to set up a press regulator. He is also tainted by his own ties to prominent figures in the scandal.

Former Murdoch editors and journalists charged with phone hacking, police bribery or other wrongdoing include Cameron's former spokesman, Andy Coulson, and ex-News of the World editor Rebekah Brooks, a friend of the prime minister.

Coulson and Brooks appeared in court Thursday on charges of paying public officials for information.

Cameron called on the press to implement Leveson's proposals quickly.

"While nobody wants to see full statutory regulation, the status quo is not an option," he said. "The system of press regulation we have is badly broken and it has let down victims badly."